A flexible connection is a ductwork or piping joint using flexible materials to accommodate movement between fixed HVAC components and equipment. These connections isolate vibration transmission, allow for thermal expansion, and compensate for minor misalignment. They are standard in modern HVAC installations.
Material Types and Applications
Flexible connections use reinforced vinyl, fabric, or rubber materials for ductwork; braided hoses or expansion loops for refrigerant and water lines. Supply and return ducts typically employ 5 to 12-inch flexible sections rated for maximum velocity of 4,000 feet per minute. Piping connections use corrugated copper tubing or braided stainless steel hoses rated for working pressures up to 500 psi.
Installation Standards
SMACNA and NFPA guidelines specify flexible connection lengths and support requirements. Typical ductwork connections measure 12 to 36 inches in length. Connections must prevent sagging and excessive movement while maintaining airtight seals. Proper support using hangers every 4 to 6 feet prevents stress concentration.
Performance Benefits
Flexible connections reduce vibration transmission by 70 to 85 percent. They prevent noise propagation through building structures and protect equipment from structural stress. Proper installation extends equipment life and maintains system performance by isolating operational vibration from building components.